Technical systems often operate with coordinate systems which they require for determining the position of occurring events, of actions to be carried out and/or of objects in motion or at rest. Sensor systems that detect the location of an event or of an object in a single- or multi-dimensional coordinate system, are examples of this. Such sensor systems can, for example, be camera-based and be configured as a motion tracking system. Such motion tracking systems are used to recognize and track the (changeable) position of moving objects.
One example of a motion tracking system especially considered within the framework of the invention is a so-called eye tracker, by which eye movements can be detected. Use of eye trackers is current practice in laser-surgery ophthalmology, thus processing of the human eye by means of laser radiation for the purpose of eliminating or at least reducing incorrect functions or pathology of the eye.
Without mechanical fixing, the human eye never is totally still, but rather even when taking aim at a specific fixation target it continues to make smaller and larger movements (such as the saccades), and therefore with various techniques of eye treatment by laser surgery, an eye tracker is used, to detect movements of the eye to be treated, and depending on the detected eye position, to guide the treating laser. As an example in this regard, especially refractive laser treatment is especially named, in which corneal tissue is ablated (i.e. removed from the surface) using laser radiation in the UV wavelength range, in this way to reform the corneal front surface and by this means to alter the refractive properties of the cornea. One example of such a refractive technique is so-called LASIK (Laser In Situ Keratomileusis), in which at first by means of a mechanical microkeratom or by means of femtosecond laser radiation, laser radiation cuts out from the cornea a small covering disk customarily designated in the technical world as a flap. The flap is not totally separated from the corner, but still hangs in a hinge area on the remaining corneal tissue. The flap is then pivoted to the side and the corneal material thus revealed is subjected to an ablating laser treatment. Then the flap is pivoted back again. Because the outer epithelium layer of the cornea is only slightly damaged in this method, the wound heals relatively quickly.
Laser devices that generate a positionally controllable laser beam for processing a material, are another example of technical systems that operate with a coordinate system. The ablation positions of the laser beam, thus those positions to which the laser beam is to be directed, can be defined by coordinate positions in the coordination system of the laser device. With laser devices that generate pulsed laser radiation, every coordinate position can be assigned to a single laser pulse or a group of laser pulses.